package java.security.cert;

import java.security.InvalidAlgorithmParameterException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Provider;
import java.security.Security;
import java.util.Collection;

/**
 * A class for retrieving <code>Certificate</code>s and <code>CRL</code>s
 * from a repository.<br />
 * <br />
 * This class uses a provider-based architecture, as described in the
 * Java Cryptography Architecture.
 * To create a <code>CertStore</code>, call one of the static
 * <code>getInstance</code> methods, passing in the type of
 * <code>CertStore</code> desired, any applicable initialization parameters 
 * and optionally the name of the provider desired. <br />
 * <br />
 * Once the <code>CertStore</code> has been created, it can be used to 
 * retrieve <code>Certificate</code>s and <code>CRL</code>s by calling its
 * {@link #getCertificates(CertSelector selector) getCertificates} and
 * {@link #getCRLs(CRLSelector selector) getCRLs} methods.<br />
 * <br />
 * Unlike a {@link java.security.KeyStore KeyStore}, which provides access
 * to a cache of private keys and trusted certificates, a 
 * <code>CertStore</code> is designed to provide access to a potentially
 * vast repository of untrusted certificates and CRLs. For example, an LDAP 
 * implementation of <code>CertStore</code> provides access to certificates
 * and CRLs stored in one or more directories using the LDAP protocol and the
 * schema as defined in the RFC service attribute. See Appendix A in the
 * Java Certification Path API Programmer's Guide for more information about
 * standard <code>CertStore</code> types.<br />
 * <br />
 * <b>Concurrent Access</b><br />
 * <br />
 * All public methods of <code>CertStore</code> objects must be thread-safe. 
 * That is, multiple threads may concurrently invoke these methods on a
 * single <code>CertStore</code> object (or more than one) with no
 * ill effects. This allows a <code>CertPathBuilder</code> to search for a
 * CRL while simultaneously searching for further certificates, for instance.<br />
 * <br />
 * The static methods of this class are also guaranteed to be thread-safe.
 * Multiple threads may concurrently invoke the static methods defined in
 * this class with no ill effects.<br />
 * <br />
 * Uses {@link CertUtil CertUtil} to actualiy load the SPI classes.
 *
 * @see CertUtil
 **/
public class CertStore extends Object
{
    private CertStoreSpi	storeSpi;
    private Provider	        provider;
    private String		type;
    private CertStoreParameters params;

	/**
	 * Creates a <code>CertStore</code> object of the given type, and
	 * encapsulates the given provider implementation (SPI object) in it.
	 *
	 * @param storeSpi the provider implementation
	 * @param provider the provider
	 * @param type the type
	 * @param params the initialization parameters (may be <code>null</code>)
	 */
    protected CertStore( CertStoreSpi storeSpi,
			 Provider provider,
			 String type,
			 CertStoreParameters params )
    {
	this.storeSpi = storeSpi;
	this.provider = provider;
	this.type = type;
	this.params = params;
    }

	/**
	 * Returns a <code>Collection</code> of <code>Certificate</code>s that
	 * match the specified selector. If no <code>Certificate</code>s
	 * match the selector, an empty <code>Collection</code> will be returned.<br />
	 * <br />
	 * For some <code>CertStore</code> types, the resulting
	 * <code>Collection</code> may not contain <b>all</b> of the
	 * <code>Certificate</code>s that match the selector. For instance,
	 * an LDAP <code>CertStore</code> may not search all entries in the
	 * directory. Instead, it may just search entries that are likely to
	 * contain the <code>Certificate</code>s it is looking for.<br />
	 * <br />
	 * Some <code>CertStore</code> implementations (especially LDAP 
	 * <code>CertStore</code>s) may throw a <code>CertStoreException</code> 
	 * unless a non-null <code>CertSelector</code> is provided that 
	 * includes specific criteria that can be used to find the certificates.
	 * Issuer and/or subject names are especially useful criteria.
	 *
	 * @param selector A <code>CertSelector</code> used to select which
	 *  <code>Certificate</code>s should be returned. Specify <code>null</code>
	 *  to return all <code>Certificate</code>s (if supported).
	 *
	 * @return A <code>Collection</code> of <code>Certificate</code>s that
	 *         match the specified selector (never <code>null</code>)
	 * @exception CertStoreException if an exception occurs 
	 */
    public final Collection getCertificates( CertSelector selector )
	throws CertStoreException
    {
	return storeSpi.engineGetCertificates( selector );
    }

	/**
	 * Returns a <code>Collection</code> of <code>CRL</code>s that
	 * match the specified selector. If no <code>CRL</code>s
	 * match the selector, an empty <code>Collection</code> will be returned.<br />
	 * <br />
	 * For some <code>CertStore</code> types, the resulting
	 * <code>Collection</code> may not contain <b>all</b> of the
	 * <code>CRL</code>s that match the selector. For instance,
	 * an LDAP <code>CertStore</code> may not search all entries in the
	 * directory. Instead, it may just search entries that are likely to
	 * contain the <code>CRL</code>s it is looking for.<br />
	 * <br />
	 * Some <code>CertStore</code> implementations (especially LDAP 
	 * <code>CertStore</code>s) may throw a <code>CertStoreException</code> 
	 * unless a non-null <code>CRLSelector</code> is provided that 
	 * includes specific criteria that can be used to find the CRLs.
	 * Issuer names and/or the certificate to be checked are especially useful.
	 *
	 * @param selector A <code>CRLSelector</code> used to select which
	 *  <code>CRL</code>s should be returned. Specify <code>null</code>
	 *  to return all <code>CRL</code>s (if supported).
	 *
	 * @return A <code>Collection</code> of <code>CRL</code>s that
	 *         match the specified selector (never <code>null</code>)
	 *
	 * @exception CertStoreException if an exception occurs 
	 */
    public final Collection getCRLs( CRLSelector selector )
	throws CertStoreException
    {
	return storeSpi.engineGetCRLs( selector );
    }

	/**
	 * Returns a <code>CertStore</code> object that implements the specified
	 * <code>CertStore</code> type and is initialized with the specified
	 * parameters.<br />
	 * <br />
	 * If the default provider package provides an implementation
	 * of the specified <code>CertStore</code> type, an instance of
	 * <code>CertStore</code> containing that implementation is returned.
	 * If the requested type is not available in the default package, other
	 * packages are searched.<br />
	 * <br />
	 * The <code>CertStore</code> that is returned is initialized with the 
	 * specified <code>CertStoreParameters</code>. The type of parameters 
	 * needed may vary between different types of <code>CertStore</code>s.
	 * Note that the specified <code>CertStoreParameters</code> object is 
	 * cloned.
	 * 
	 * @param type the name of the requested <code>CertStore</code> type
	 * @param params the initialization parameters (may be <code>null</code>)
	 *
	 * @return a <code>CertStore</code> object that implements the specified
	 *  <code>CertStore</code> type
	 *
	 * @exception NoSuchAlgorithmException if the requested type is not
	 *  available in the default provider package or any of the other provider
	 *  packages that were searched
	 * @exception InvalidAlgorithmParameterException if the specified
	 * initialization parameters are inappropriate for this 
	 * <code>CertStore</code>
	 */
    public static CertStore getInstance( String type,
					 CertStoreParameters params)
	throws InvalidAlgorithmParameterException,
	NoSuchAlgorithmException
    {
	try {
	    CertUtil.Implementation  imp =
		CertUtil.getImplementation( "CertStore", type, (String)null,
					    new Class[] { CertStoreParameters.class },
					    new Object[] { params } );
	    if (imp != null)
	    {
		return new CertStore((CertStoreSpi)imp.getEngine(), imp.getProvider(), type, params );
	    }
	} catch ( NoSuchProviderException ex ) {}
	throw new NoSuchAlgorithmException("can't find type " + type);
    }

	/**
	 * Returns a <code>CertStore</code> object that implements the specified
	 * <code>CertStore</code> type, as supplied by the specified provider
	 * and initialized with the specified parameters.<br />
	 * <br />
	 * The <code>CertStore</code> that is returned is initialized with the 
	 * specified <code>CertStoreParameters</code>. The type of parameters 
	 * needed may vary between different types of <code>CertStore</code>s.
	 * Note that the specified <code>CertStoreParameters</code> object is 
	 * cloned.
	 *
	 * @param type the requested <code>CertStore</code> type
	 * @param params the initialization parameters (may be <code>null</code>)
	 * @param provider the name of the provider
	 *
	 * @return a <code>CertStore</code> object that implements the
	 * specified type, as supplied by the specified provider
	 *
	 * @exception NoSuchAlgorithmException if the requested type is not
	 *  available from the specified provider
	 * @exception InvalidAlgorithmParameterException if the specified
	 * initialization parameters are inappropriate for this 
	 * <code>CertStore</code>
	 * @exception NoSuchProviderException if the provider has not been configured
	 * @exception IllegalArgumentException if the <code>provider</code> is
	 * null
	 */
    public static CertStore getInstance( String type,
					 CertStoreParameters params,
					 String provider)
	throws InvalidAlgorithmParameterException,
	NoSuchAlgorithmException,
	NoSuchProviderException,
	IllegalArgumentException 
    {
	if ( provider == null )
	    throw new IllegalArgumentException( "provider must be non-null" );

	CertUtil.Implementation  imp =
	    CertUtil.getImplementation( "CertStore", type, provider,
					new Class[] { CertStoreParameters.class },
					new Object[] { params } );
	if (imp != null)
	{
	    return new CertStore((CertStoreSpi)imp.getEngine(), imp.getProvider(), type, params );
	}
	throw new NoSuchAlgorithmException("can't find type " + type);
    }
    
	/**
	 * Returns a <code>CertStore</code> object that implements the specified
	 * <code>CertStore</code> type, as supplied by the specified provider and
	 * initialized with the specified parameters.
	 * Note: the <code>provider</code> doesn't have to be registered.<br />
	 * <br />
	 * The <code>CertStore</code> that is returned is initialized with the 
	 * specified <code>CertStoreParameters</code>. The type of parameters 
	 * needed may vary between different types of <code>CertStore</code>s.
	 * Note that the specified <code>CertStoreParameters</code> object is 
	 * cloned.
	 *
	 * @param type the requested <code>CertStore</code> type
	 * @param params the initialization parameters (may be <code>null</code>)
	 * @param provider the provider
	 *
	 * @return a <code>CertStore</code> object that implements the
	 * specified type, as supplied by the specified provider
	 *
	 * @exception NoSuchAlgorithmException if the requested type is not
	 *  available from the specified provider
	 * @exception InvalidAlgorithmParameterException if the specified
	 * initialization parameters are inappropriate for this 
	 * <code>CertStore</code>
	 * @exception IllegalArgumentException if the <code>provider</code> is
	 * null 
	 */
    public static CertStore getInstance( String type,
					 CertStoreParameters params,
					 Provider provider )
	throws NoSuchAlgorithmException,
	InvalidAlgorithmParameterException,
	IllegalArgumentException
    {
	if ( provider == null )
	    throw new IllegalArgumentException( "provider must be non-null" );
	CertUtil.Implementation imp =
	    CertUtil.getImplementation( "CertStore", type, provider,
					new Class[] { CertStoreParameters.class },
					new Object[] { params } );
	if (imp != null)
	{
	    return new CertStore((CertStoreSpi)imp.getEngine(), provider, type, params );
	}
	throw new NoSuchAlgorithmException("can't find type " + type);
    }

	/**
	 * Returns the parameters used to initialize this <code>CertStore</code>.
	 * Note that the <code>CertStoreParameters</code> object is cloned before 
	 * it is returned.
	 *
	 * @return the parameters used to initialize this <code>CertStore</code>
	 * (may be <code>null</code>)
	 */
    public final CertStoreParameters getCertStoreParameters()
    {
	return params;
    }

	/**
	 * Returns the type of this <code>CertStore</code>.
	 *
	 * @return the type of this <code>CertStore</code>
	 */
    public final String getType()
    {
	return type;
    }

	/**
	 * Returns the provider of this <code>CertStore</code>.
	 *
	 * @return the provider of this <code>CertStore</code>
	 */
    public final Provider getProvider()
    {
	return provider;
    }

	/**
	 * Returns the default <code>CertStore</code> type as specified in the 
	 * Java security properties file, or the string &quot;LDAP&quot; if no 
	 * such property exists. The Java security properties file is located in 
	 * the file named &lt;JAVA_HOME&gt;/lib/security/java.security, where 
	 * &lt;JAVA_HOME&gt; refers to the directory where the SDK was installed.<br />
	 * <br />
	 * The default <code>CertStore</code> type can be used by applications 
	 * that do not want to use a hard-coded type when calling one of the
	 * <code>getInstance</code> methods, and want to provide a default 
	 * <code>CertStore</code> type in case a user does not specify its own.<br />
	 * <br />
	 * The default <code>CertStore</code> type can be changed by setting 
	 * the value of the "certstore.type" security property (in the Java 
	 * security properties file) to the desired type.
	 *
	 * @return the default <code>CertStore</code> type as specified in the
	 * Java security properties file, or the string &quot;LDAP&quot;
	 * if no such property exists.
	 */
    public static final String getDefaultType()
    {
	String defaulttype = null;
	defaulttype = Security.getProperty("certstore.type");

	if ( defaulttype == null || defaulttype.length() <= 0 )
	    return "LDAP";
	else
	    return defaulttype;
    }
}

